1. Technical Field
This invention generally relates to a flexible endless conveyor belt having a fold-over capability for conveying relatively-loose bulk material from one point to another especially along steep inclines and declines, the belt cover-flaps completely enclosing the load while it is conveyed.
2. Background Information
The subject invention which relates to an endless folding belt adapted for use in belt conveyor systems provides a significant improvement in such systems wherein the belt has a substantially longer service life at its hinged areas.
The belt is adapted for use in conveyor systems to move the folding belt by drive rolls while supported in intermediate areas on idler rolls, the belt having a pair of continuous flexible longitudinal cover or hinge flaps which permit the flaps to be folded and unfolded to facilitate loading and unloading of the belt at several load handling stations or positions. The folding belt is normally folded to enclose bulk materials during their transport from one position to another to eliminate spillage of the load or its contamination during transport and to permit the load to move along steep inclines and declines. The folding belt is capable of carrying significantly greater loads without producing dust-emitting conditions in the vicinity of the belt, the belt having an improved construction in its hinged areas for much longer-service life.
Prior forms of such folding belts have heretofore utilized single and multiple grooves at their hinged areas on the load-carrying side of the belt. This places a much larger bending moment on the belt in obtaining a hinged effect wherein the belt is essentially folded on itself at the pair of similarly grooved areas. Where the belt is formed from flexible elastomeric material, the interior grooves are compressed in a severe deleterious manner which shortens belt life where the belts are employed to carry significantly greater volumes of bulk material between loading and unloading positions. Belts having such single grooves at the hinged areas on the load-carrying side of the belts are disclosed in U.S. Pat. No. 4,709,806, along with known types of conveyor systems for transport of loose materials in an enclosed manner. While the interiorly grooved hinged areas have been used previously, the amount of undue stress placed on the belt at the hinged areas causes excessive wear and material carried on the belt is often caught in the grooves, prematurely wearing the belt and reducing belt life.
Prior to the advent of fold-over belts, open belts have been used previously in the art to convey bulk materials in a manner open to the atmosphere. In view of inherent dusting problems, the industry has utilized metal shrouding or other forms of enclosure of the belt to eliminate contamination dusting and to maintain the conveyed material in an essentially clean and uncontaminated condition. The use of shrouding occasionally results in accumulation of dust and in some cases a creation of explosive mixtures which occurrences are particularly dangerous and to be avoided. Prior to the use of folding-belt conveyor systems, such systems were objectionable in allowing spillage of the conveyed material frequently due to belt construction and its mounting for continuous movement. There has been a need in the art for an improved fold-over belt structure having much longer service life which requires lesser maintenance and downtime due to belt failure or weaknesses requiring costly belt replacement.
U.S. Pat. No. 5,107,983, issued to William H. Tschantz, the inventor of the present invention, which patent is incorporated herein by reference, describes an endless fold-over type of conveyor belt that has a group of closely-spaced longitudinal grooves located on the load-carrying side of the belt. The longitudinal grooved areas are located proximate the edges of the belt and form a hinged area for folding and unfolding the belt. While this belt works fairly well, some problems have been experienced in the conveying of loosely-packed materials such as loose sugar. This type of material tends to become lodged in the grooves and, because of the stickiness of the product, some of the material tends to remain in the grooves after the conveyor has been unloaded. Some of the endless conveyor belts may be of considerable length. Over time the material in the grooves on these long belts may build up to the point that the additional weight on the belt places an unacceptable strain on the motors driving the belt. The material trapped in the grooves may also abrade the belt causing premature wear. Additionally, these belts have been manufactured with the load-carrying side of the belt being made of a softer surface material so that they can be more easily folded at the grooves. When harder load materials, such as coal, are carried on such belts, the hard load material may damage the belt and cause it to delaminate more easily.
Furthermore, since fold-over belts can go up steep angles due to the pressure of the top flaps trapping material against the bottom carrying side of the belt, it is desirable that the belt have a controlled cross section so that the material will not slide back along the belt in steep angles. Therefore, it is desirable to close the top flaps as much as possible to match the cross sectional area of the belt to the material being carried thereby. When the grooves are formed in the load carrying surface the top flaps are held in compression by overhead rollers. This compression may also cause the belt to delaminate prematurely.